Paint sludge poses a serious and expensive waste disposal problem for painting operations in manufacturing plants. When an object such as an automobile assembly or component is painted in a paint spray booth, the excess paint or overspray is typically collected in a water curtain and/or in a water stream underneath floor grating beneath the paint booth. This collected material is known as paint sludge. Disposing of paint sludge waste poses a problem of considerable complexity to paint booth operators. Current disposal technology is based upon incineration, or chemical and/or physical treatment together with solidification for purposes of landfill disposal. However, the disposal of paint sludge in landfills raises environmental concerns due to the fact that paint sludge typically contains numerous hazardous components. Such environmental concerns create the potential for long term liabilities and incur costs for special precautions that are needed to handle such waste materials.
Attempts have been made to create useful byproducts from paint sludge in order to gain or recover some value and lower the overall costs of processing the paint waste. Most of these attempts involved complex, potentially dangerous and problematic processing steps which add to the overall processing costs. Such high costs severely limit commercial interest in processing paint sludge.
U.S. Pat. No. 5,004,550 to Beckman et al. discloses a method for disposing of paint sludge that involves the addition of detackification agents to paint sludge in order to float the resulting product out of a paint sludge pit.
U.S. Pat. No. 5,160,628 to Gerace et al. discloses a method for making a filler from automotive paint sludge which involves a two-step process for handling paint sludge. In a first step Gerace et al. requires the mechanical removable of water from paint sludge. In the second step Gerace et al. uses chemical drying agents to remove further water and to produce a dried paint sludge powder containing uncured polymer.
U.S. Pat. No. 5,259,977 to Girovich et al. discloses a method and apparatus for the treatment of sewage sludge. Girovich et al teaches the desirability of an agglomerization or pelletization step in the treatment of organic sludge and discloses the use of quicklime in the treatment of organic sludge for the purposes of diminishing odors and neutralizing pathogens.
U.S. Pat. No. 5,489,333 to Soroushian et al. discloses the use of dried paint sludge powder as a filler admixed in Portland cement.
U.S. Pat. No. 5,573,587 to St. Louis discloses a method of paint sludge conversion that is used to produce building materials. St. Louis teaches pretreating paint sludge with sodium hydroxide before chemically drying the sludge.
U.S. Pat. No. 5,573,587 to St. Louis discloses mixing raw paint sludge with quicklime (CaO) to chemically dry the sludge and thereafter creating a powder of paint solids and slaked lime which is used as a component for use in mortar, cement, concrete and asphalt.
U.S. Pat. No. 6,673,322 to Santilli discloses a device for converting waste material into a fuel using a complex and potentially dangerous electric arc process to convert the molecular structure of these wastes into fuel.
Other patents that disclose various manners of processing paint sludge include U.S. Pat. No. 4,303,559 to Trost, U.S. Pat. No. 4,423,688 to Kuo, U.S. Pat. No. 4,426,936 to Kuo, U.S. Pat. No. 4,436,037 to Kuo and U.S. Pat. No. 6,119,607 to Guy et al.
Processing of paint sludge is time consuming and costly. Accordingly, there is need for a simple process that effectively collects and uses all of the paint sludge solids generated by paint booth facilities.
Landfill disposal of paint sludge is an environmentally undesirable method of disposing of waste paint sludge. Accordingly, there is a need for a better alternative method for disposal or recycling of waste paint sludge.
The present invention provides a simple and economic process for collecting, processing and using all of the paint sludge solids generated by paint booth facilities. Moreover, the present invention provides a method of producing a combustible fuel product from paint sludge which can be used to supplement fuel supplies used in power and heat generating plants and similar facilities and applications.